/* /css/common.css */
:root {
    /* Light Mode Colors */
    --bg-color: #f3f4f6;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --shadow: 0 1px 3px rgba(0, 0, 0, .08);
    --icon-color: #6b7280;
    --success-color: #10b981;
    --error-color: #ef4444;
    --emerald-500: #10b981;
    --emerald-600: #059669;

    /* Chat-specific variables */
    --header-bg: #ffffff;
    --bubble-me: #10b981;
    --bubble-other: #ffffff;
    --input-area-bg: #ffffff;
    --input-bg: #f3f4f6;

    /* Login-specific variables */
    --card-color: #ffffff;
    --input-border: #d1d5db;
}

body.dark-mode {
    /* Dark Mode Colors */
    --bg-color: #111827;
    --text-primary: #f9fafb;
    --text-secondary: #9ca3af;
    --border-color: #374151;
    --shadow: 0 1px 3px rgba(0, 0, 0, .1);
    --icon-color: #9ca3af;

    /* Chat-specific variables */
    --header-bg: #1f2937;
    --bubble-other: #374151;
    --input-area-bg: #1f2937;
    --input-bg: #374151;

    /* Login-specific variables */
    --card-color: #1f2937;
    --input-border: #4b5563;
}

* {
    box-sizing: border-box;
}

html,
body {
    height: 100%;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'WenQuanYi Micro Hei', sans-serif;
    background: var(--bg-color);
    color: var(--text-primary);
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* --- Unified Header Styles --- */
.header {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    /* Left, Center, Right */
    align-items: center;
    padding: 0 1rem;
    height: 60px;
    background-color: var(--header-bg);
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
    box-shadow: var(--shadow);
    transition: background-color 0.3s, border-color 0.3s;
    position: sticky;
    top: 0;
    z-index: 10;
}

.header-left {
    justify-self: start;
}

.header-center {
    justify-self: center;
}

.header-right {
    justify-self: end;
}

.header h1 {
    font-size: 1.25rem;
    font-weight: 600;
    margin: 0;
    color: var(--text-primary);
}

/* Common button styles */
.theme-btn,
.lang-btn {
    padding: 0.5rem;
    border-radius: 0.5rem;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    transition: all 0.2s ease;
    background-color: transparent;
    border: none;
}

.theme-btn:hover,
.lang-btn:hover {
    background-color: var(--bg-color);
}


.theme-btn svg {
    width: 1.5rem;
    height: 1.5rem;
}

.lang-btn {
    font-size: 0.875rem;
    padding: 0.5rem 1rem;
    width: auto;
}

/* --- Common Form Styles --- */
.form-group {
    margin-bottom: 0.75rem;
}

.form-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 700;
    margin-bottom: 0.25rem;
    color: var(--text-primary);
}

.form-input {
    box-shadow: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    appearance: none;
    border: 1px solid var(--input-border);
    border-radius: 0.5rem;
    width: 100%;
    padding: 0.75rem 1rem;
    background-color: var(--input-bg);
    color: var(--text-primary);
    line-height: 1.25;
    box-sizing: border-box;
    transition: background-color 0.3s, border-color 0.3s, color 0.3s;
}

.form-input:focus {
    outline: 2px solid transparent;
    outline-offset: 2px;
    border-color: var(--emerald-500);
    box-shadow: 0 0 0 2px var(--emerald-500);
}

.gender-options {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    padding-top: 0.25rem;
}

.gender-options label {
    font-weight: normal;
    margin-bottom: 0;
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

/* --- Common Button Styles --- */
.btn {
    display: inline-flex;
    /* Use flex for alignment */
    justify-content: center;
    align-items: center;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    font-weight: 700;
    cursor: pointer;
    border: 1px solid transparent;
    transition: background-color 0.2s ease, opacity 0.2s ease, color 0.2s, border-color 0.2s;
    text-align: center;
}

.btn-block {
    width: 100%;
}

.btn-primary {
    background-color: var(--emerald-500);
    color: #ffffff;
    border-color: var(--emerald-500);
}

.btn-primary:hover {
    background-color: var(--emerald-600);
}

.btn-primary:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.btn-secondary {
    background-color: var(--bg-color);
    border-color: var(--border-color);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background-color: var(--border-color);
}